// 代码整理：懒人之家 www.lanrenzhijia.com
 (function(){
        function G(s) {
            return document.getElementById(s);
        }
        function getStyle(obj, attr) {
            if (obj.currentStyle) {
                return obj.currentStyle[attr];
            } else {
                return getComputedStyle(obj, false)[attr];
            }
        }
        function Animate(obj, json) {
            if (obj.timer) {
                clearInterval(obj.timer);
            }
            obj.timer = setInterval(function(){
                for (var attr in json) {
                    var iCur = parseInt(getStyle(obj, attr));
                    iCur = iCur ? iCur : 0;
                    var iSpeed = (json[attr] - iCur) / 5;
                    iSpeed = iSpeed > 0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);
                    obj.style[attr] = iCur + iSpeed + 'px';
                    if(iCur == json[attr]){
                        clearInterval(obj.timer);
                    }
                }
            }, 30);
        }

        var oPic = G("picBox");
        var oList = G("listBox");

        var oPrev = G("prev");
        var oNext = G("next");
        var oPrevTop = G("prevTop");
        var oNextTop = G("nextTop");

        var oPicLi = oPic.getElementsByTagName("li");
        var oListLi = oList.getElementsByTagName("li");
        var len1 = oPicLi.length;
        var len2 = oListLi.length;

        var oPicUl = oPic.getElementsByTagName("ul")[0];
        var oListUl = oList.getElementsByTagName("ul")[0];
        var w1 = oPicLi[0].offsetWidth;
        var w2 = oListLi[0].offsetWidth;

        oPicUl.style.width = w1 * len1 + "px";
        oListUl.style.width = w2 * len2 + "px";

        var index = 0;

        var num = 5;
        var num2 = Math.ceil(num / 2);

        function Change() {

            Animate(oPicUl, {left: - index * w1});

            if(index < num2){
                Animate(oListUl, {left: 0});
            }else if(index + num2 <= len2){
                Animate(oListUl, {left: - (index - num2 + 1) * w2});
            }else{
                Animate(oListUl, {left: - (len2 - num) * w2});
            }

            for (var i = 0; i < len2; i++) {
                oListLi[i].className = "";
                if(i == index){
                    oListLi[i].className = "on";
                }
            }
        }
        oNextTop.onclick = oNext.onclick = function(){
            index ++;
            index = index == len2 ? 0 : index;
            Change();
        }
        oPrevTop.onclick = oPrev.onclick = function(){
            index --;
            index = index == -1 ? len2 -1 : index;
            Change();
        }
        for (var i = 0; i < len2; i++) {
            oListLi[i].index = i;
            oListLi[i].onclick = function(){
                index = this.index;
                Change();
            }
        }
        })()
 // 代码整理：懒人之家 www.lanrenzhijia.com